We have recently launched a new core type for bigadv work units. We're forking A5 off from our A3 core to make a core that specializes in bigadv workunits. In particular, new A3 and A4 cores use more RAM per thread which makes large-memory calculations very memory inefficient in those cores. A5 does not have this issue and looks to be a good general fix for big RAM (eg bigadv) calculations.